John Martz (d. 2013) is known as the foremost name of custom Luger and P-38 pistols, including upgraded calibers and carbine conversions. His pieces are listed in the "Blue Book of Gun Values" and the "Standard Catalog of Firearms". The Blue Book records that only 30 P-38s were carbine converted by Martz. In contrast to the Luger conversions, the P-38 conversion presented interesting engineering challenges; the second most pressing being the lack of an "original" P-38 Carbine to use as a guideline and reference, but the most critical being the complete absence of structural metal in the relevant area, as a conventional P-38 has exposed spring and magazine catch hardware on the back strap, which are protected by thin plastic grip panels that wouldn't bear the load of a stock, or cope well with recoil forces. A significant quantity of steel has been added to the back strap of a Walther "eagle/359" proofed frame, enabling a High Power-style stock slot to be created whole-cloth by Martz. A custom extended barrel has been sleeved into a Walther "359" proofed barrel lug/chamber assembly, with a standard blade front sight and a fixed notch rear sight just ahead of the chamber, emulating the placement of the Luger Carbine sight. The slide is free of proof marks, with "P.38 AC45 " added to the left side and a smooth rounded block in the traditional rear sight slot. In addition to the stock slot, the frame is fitted with a 4 1/4 inch long hanging iron for the forearm and stamped "JVM" and "12" beneath the barrel latch. A smooth Schnabel-tip forearm is secured to the iron with a steel wedge and a threaded screw that doubles as a sling swivel, and the grips are checkered with a right handed thumbrest and appropriate slotting to accommodate the back strap extension. The buttstock is crafted from fine hardwood, with an unnumbered bright steel mounting iron and a contoured naked butt. One post-WWII commercial magazine is included, with the base polished to match the exterior. Included with the lot is a brown leather sling and a custom hardwood case with a deep French cut interior with space for all of the above listed items and extra spaces for an additional magazine and ammunition/tools.

Very fine as custom upgraded, with polished bright custom finish, showing some mild handling marks overall and a small brown spot on the left rear corner of the magazine well. The wood furniture is near mint, with some light handling marks. The case is also near mint, with some light rubs and dings. Mechanically excellent. A very rare master crafted variant of the historic P-38 semi-automatic pistol.